Toward rapid aqueous RAFT polymerization of primary amine functional monomer under visible light irradiation at 25 °C

Abstract

We report the rapid and well-controlled aqueous RAFT polymerization of primary amine functional monomer under visible light irradiation at 25 °C. N-(2-aminoethyl)methacrylamide hydrochloride (AEMA) and N-(6-aminohexyl)methacrylamide hydrochloride (AHMA) were synthesized as prototypes of primary amine functional monomers. The results demonstrated that this polymerization proceeded rapidly in a well-controlled manner in acidic aqueous media upon irradiating with mild visible light at 25 °C. Moreover, improving the ion-pairing or association of the ionized monomers via adding less polar alcohols or improving the concentration of ionized monomers could shorten the initialization period and accelerate chain propagation, thus remarkably accelerating this polymerization. This polymerization was immediately switched on or off via turning on or off visible light. Dithioester residues at polymer chain ends could be retained or removed simply by adjusting pH. Accordingly, this paper provides a facile approach toward direct and rapid RAFT synthesis of well-defined primary amine functional polymers at room temperature.